Development of the electric furnace for the growth of relaxor type ferroelectrics single crystal and development of the crystal growth technique.

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Electric furnace for the crystal growth, which make an aim to large and high quality ferroelectrics single crystals, are designed and produced. The specification for electric furnace are as follows. Ordinary temperature : 1500℃, maximum temperature : 1550℃, soaking space in electric furnace, 150 X 150 X 150H mm (the crucihle installation position), temperature control is excused by PID program controller, which can communicate the personal computer using RS-232Cinterface, that records the furnace temperature automatically. In the case of abnormal occurrence, electric furnace breaks a circuit automatically to stop power supply.Recently much attention has been given to relaxor type ferroelectrics from view point of fundamental interest and practical development of some electronic devices. In this work, Relaxor type ferroelectrics (1-x)Pb(Zn_<1/3>Nb_<2/3>)0_3-xPbTi0_3 and (1-x)Pb(Mn_<1/3>Nb_<2/3>)O_3-xPbTi0_3 were grown by using of PbO flux solution method. Processing conditions were investigated to increase the size and yield of the perovskite crystals, including variation of the flux to composition ratio, cooling rate, soak time and soak temperature. The crystals varied in size from 1 mm to 3.5 mm on an edge, and in color from opaque to brown due to the changes in some processing conditions. The furnace temperature reached 1180ーC, soaking time is from 5 to 10 hours, cooling rate is -2℃ per hour from 1180℃ to 850℃. These conditions are suitable for crystal growth. The crystals were characterized by X-ray diffraction, dielectric constant and dielectric loss measurements.